Display type cooler or freezer chests are known in which air is circulated in order to cool the articles therein. In this type of chest a very small quantity of the cooled air flows out of the circulation path at the open side thereof. This quantity of cooled air is replaced by warm atmospheric air which is drawn into the circulating channel in the chest and deposits its contents of moisture. This moisture, unfortunately, will successively settle in the form of frost on the cooling elements in the channel. Thus, it is necessary to defrost the cooling elements at regular intervals in order to maintain the cooling efficiencies of the elements of the display chest. For the foregoing purpose, it is known to provide electric elements which are placed alongside the cooling elements. Thereafter, the cooling compressor is shut off and heat is applied to the electrical elements. Simultaneously, fans are operated so that the circulation of air continues. This method results in a relatively rapid defrosting of the elements. However, a substantial increase in the electrical input rate is the result, and an expensive assembly of electric elements with connecting wires are required. Therefore, in order to avoid the disadvantages of the foregoing method, it has been proposed to use heat from the atmosphere circulating about the chest. Thus, display cooler and freezer chests have been made with special air channels through the walls for supplying warm atmospheric air and removing the cold air which, during defrosting, is cooled by the cooling elements. As a result, there will be no longer a circulating quantity of air in a display cooler or freezer chest. However, this method is more complicated because, in addition to the extra air channels, a system of movable flaps is required. These movable flaps must be reset before and after defrosting so that the desired air paths are obtained. In addition, the foregoing method has another disadvantage in that the defrosting means involves an increased cost for a display cooler and freezer chest, and further that they are an additional source of operational disturbance. Consequently, the latter method also entails increased requirements for supervision of the defrosting procedure. A prior art construction is shown in Finnish Patent Application No. 1314/70 filed May 11, 1970 and published on Apr. 30, 1971, and issued as Finnish Pat. No. 44010, in which an air channel for warm air is shown directing the latter to a cooled air channel.
In order to avoid the drawbacks of the known methods of defrosting a display cooler or freezer it is a principal feature of the present invention to provide defrosting of a display cooler or freezer by a simple and reliable means without any significant increase of cost, as well as of the rated electrical input. In order to achieve the foregoing improvement the invention is generally characterized in that an intake for the circulating air is blocked and warm atmospheric air is directed from a place outside of the circulation path to the intake in order to be conveyed by fans through the cooling elements in the channel and out to the atmosphere through the normal outlet opening.
A further feature of the present invention is that the guide member during defrosting forms an intake for air to the channel from a location having warm atmospheric air outside of the circulation path, with the channel for the rest of the air being unchanged so that the air is discharged through the normal outlet opening.